In some radio frequency (RF) communication receivers, wide acquisition range is required due to uncertainty as to the RF carrier frequency. One example is a television (TV) receiver, where an acquisition range of up to 2 megahertz (MHz) is required. The assumption is that knowledge about existing TV channels frequency is not accurate at a television due to a great variety of transmission standards and frequency spectrum allocation plans around the world, as well as possible transmission frequency offsets at various local areas. Typically, receivers need to conduct two tasks, namely, channel acquisition and carrier tracking. The channel acquisition task operates with a wide acquisition range and the carrier tracking task operates with a relatively narrow tracking range. Typically, different circuitry is used to perform these two different tasks, leading to an increase in costs, and in semiconductor-based solutions an increase in die area.
Once a channel frequency is acquired through wideband acquisition, it can be tracked using a phase lock loop (PLL). Most PLLs have a relatively small operating range, e.g., usually tens of kilohertz (kHz) for loop stability and noise performance. Since there is typically insufficient frequency information available when a channel is selected, the frequency acquisition mode attempts to perform a coarse estimate of the carrier frequency so that once this estimate is known, it can be used to align the PLL to lock.